1. Field of the Invention
The present invention is in the field of bone implants, particularly dental implants.
2. Related Art
In spite of the greatest care in insertion of the base part of an implant into the jawbone, it is impossible to avoid subsequent adjustments as part of the prosthetic final servicing to achieve the required correct tooth position. To the extent that the implant superstructural part that will be inserted into the base part does not already have design features that allow subsequent correction or adjustment to the correct tooth position—DE 41 27 839 A1, screw implants, especially those made in a single piece—EP 1 468 658 A1, DE 203 06 008 U1, DE 39 18 309 C2—but also multi-part enossal implants—U.S. Pat. No. 4,645,435—have bendable sections or bending zones which make the required adjustments easier. These bendable sections are provided in the head region of the implant, below a cementation post or an abutment, and are formed by constrictions with a reduced profile cross-section.
The bendable segments designed in that manner provide, in an advantageous manner, for alignment of the implant head with the cementation post or the abutment with respect to the part of the implant inserted into the jawbone. But they also have the disadvantage that even with extreme care there is a high risk of breakage during the bending that must be done, because of the reduced profile cross-section in the neck region.
However, there is also a high risk of breakage in the final phase of the insertion, if the implant is already positioned relatively deeply within the jawbone but has not yet attained its final position, and a higher torque must be applied for further screwing the screw implant into the jawbone to attain its final position. This high risk of breakage occurs primarily if the implant bed has not been sufficiently prepared. After a break in the bendable neck region, it is extremely difficult and expensive to remove the broken implant, which has been inserted relatively solidly and deeply. But the broken implant must be removed so that the implant bed can be prepared again and a new or different implant can be inserted.
Maintaining the stability of enossal implants with respect to the bones into which they are placed is anther problem. Mobility of implants is often observed both in orthopedic surgery and in dental and maxillofacial implantology. A certain portion of that mobility is due to infection. However, most of the mobility is caused by overloading the peri-implant bone. For instance, it is the most highly stressed screws, or the screws positioned in the least mineralized regions, such as in the tension or flexion regions of the bone, that become mobile in the case of fractured osteotomy plates.
The measures that have been known to limit or prevent these undesired processes amount to promoting new bone formation in the bony surgical region. Thus it has been suggested, among other things, to accelerate and stimulate the formation of new bony tissue by coating the implant surface with substances that promote bone growth.
Such procedures, and recommendations are, for instance, known from DE 600 19 752 T2, DE 196 30 034 A1 and DE 196 28 464 A1. They relate predominantly to improved preparation of substrates for bone development, such as tricalcium phosphate, hydroxyapatite, and all sorts of calcium and phosphorus compounds.
Measures for improved blood supply to the bone were also recommended to accelerate and stimulate formation of new bone tissue. Finally, increased provision of growth hormones and peptides of all types, which accelerate bone development, have been recommended.
None of those efforts has yet resulted in an actual useful and good clinical result, and there has been no overwhelming success in clinical practice, as it takes many weeks to months before the newly formed bone truly mineralizes and becomes capable of bearing a load. The implant mobility mentioned occurs much sooner, though.
Therefore the invention is based on the objective of reducing the disadvantages connected with breakage of the screw implant in the head and neck region with simultaneous improvement of the bendability in the neck region of the implant, and, by means of a suitable coating, to produce a microtherapeutic reduction of the osteonal activity, so as to prevent in that manner destabilization of the inserted implant.
The present invention concerns a further-improved enossal screw implant that is inserted cortically into the jawbone as an implant base, and which has at its head end a neck region with a bending zone, to which an abutment connects for holding and fastening the superstructural part of a tooth replacement or a substructure.